Add API paddle.neg() and paddle.lgamma(), along with some unittests for paddle.neg().

python/paddle/__init__.py

@@ -206,6 +206,7 @@
 from .tensor.math import prod  # noqa: F401
 from .tensor.math import broadcast_shape  # noqa: F401
 from .tensor.math import conj  # noqa: F401
+from .tensor.math import neg  # noqa: F401
 
 from .tensor.random import multinomial  # noqa: F401
 from .tensor.random import standard_normal  # noqa: F401
@@ -422,6 +423,7 @@
            'prod',
            'broadcast_shape',
            'conj',
+           'neg',
            'square',
            'divide',
            'ceil',

python/paddle/fluid/tests/unittests/test_neg_op.py

@@ -0,0 +1,91 @@
+#   Copyright (c) 2021 PaddlePaddle Authors. All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import unittest
+import numpy as np
+import paddle
+
+
+class TestNegOp(unittest.TestCase):
+    def setUp(self):
+        self.init_dtype_type()
+        self.input = np.random.random((32, 8)).astype(self.dtype)
+
+    def init_dtype_type(self):
+        self.dtype = np.float64
+
+    def run_imperative(self):
+        input = paddle.to_tensor(self.input)
+        dy_result = paddle.neg(input)
+        expected_result = np.negative(self.input)
+        self.assertTrue(np.allclose(dy_result.numpy(), expected_result))
+
+    def run_static(self, use_gpu=False):
+        input = paddle.fluid.data(name='input', shape=[32, 8], dtype=self.dtype)
+        result = paddle.neg(input)
+
+        place = paddle.CUDAPlace(0) if use_gpu else paddle.CPUPlace()
+        exe = paddle.static.Executor(place)
+        exe.run(paddle.static.default_startup_program())
+        st_result = exe.run(feed={"input": self.input}, fetch_list=[result])
+        expected_result = np.negative(self.input)
+        self.assertTrue(np.allclose(st_result[0], expected_result))
+
+    def test_cpu(self):
+        paddle.disable_static(place=paddle.CPUPlace())
+        self.run_imperative()
+        paddle.enable_static()
+
+        with paddle.static.program_guard(paddle.static.Program()):
+            self.run_static()
+
+    def test_gpu(self):
+        if not paddle.fluid.core.is_compiled_with_cuda():
+            return
+
+        paddle.disable_static(place=paddle.CUDAPlace(0))
+        self.run_imperative()
+        paddle.enable_static()
+
+        with paddle.static.program_guard(paddle.static.Program()):
+            self.run_static(use_gpu=True)
+
+
+class TestNegOpFp32(TestNegOp):
+    def init_dtype_type(self):
+        self.dtype = np.float32
+
+
+class TestNegOpInt64(TestNegOp):
+    def init_dtype_type(self):
+        self.dtype = np.int64
+
+
+class TestNegOpInt32(TestNegOp):
+    def init_dtype_type(self):
+        self.dtype = np.int32
+
+
+class TestNegOpInt16(TestNegOp):
+    def init_dtype_type(self):
+        self.dtype = np.int16
+
+
+class TestNegOpInt8(TestNegOp):
+    def init_dtype_type(self):
+        self.dtype = np.int8
+
+
+if __name__ == "__main__":
+    unittest.main()

python/paddle/tensor/math.py

@@ -2280,3 +2280,27 @@ def conj(x, name=None):
 
     helper.append_op(type='conj', inputs={'X': x}, outputs={'Out': [out]})
     return out
+
+def neg(x, name=None):
+    """
+    This function computes the negative of the Tensor elementwisely.
+
+    Args:
+        x (Tensor): Input of neg operator, an N-D Tensor, with data type float32, float64, int8, int16, int32, or int64.
+        name (str, optional): Name for the operation (optional, default is None). For more information, please refer to :ref:`api_guide_Name`.
+
+    Returns:
+        out (Tensor): The negative of input. The shape and data type are the same with input.
+
+    Examples:
+        .. code-block:: python
+
+            import paddle
+
+            x = paddle.to_tensor([-0.4, -0.2, 0.1, 0.3])
+            out = paddle.neg(x)
+            print(out)
+            # [0.4 0.2 -0.1 -0.3]
+    """
+
+    return layers.scale(x, scale=-1.0, bias=0.0, bias_after_scale=True, act=None, name=name)